Just wanted to give tips of combining slightly older chicks, with newly hatched chicks. I have done this successfully in the past, and thought I would share my experience. Above is my most recent example. The little yellow chick (Daisy)to the left, under the red one is almost 2 weeks behind the others. When she hatched, I waited until she was fluffed and dry and scooting about. Then I took her and put her in her own brooder. I had a separate brooder with the 2 week old chicks and chose 2 that were the calmest. I had her in with them for 3 days and when she was running and hopping and eating, I combined brooders. She had learned not to be afraid, and the other chicks accepted her right away. Below is a newly hatched chick raised with 3 week olds, now I did this differently... The new hatched chick above with a 3 week old. I introduced 3 older chicks with the new chick, I put them together in the dark one at a time. They snuggled and talked to each other, then all became friends, after a day or so. When introducing, be sure there is always good supervision. Good luck blending!